Hi. That's an interesting suggestion!

I guess that should be rather easy to implement using a PriorityQueue. In fact, refactoring MQ is a current project (see #2160) and we can think about including this feature. We would just need to add a parameter priority to DelayQueue that's used if the DelayQueue has a parent. Then you could do

MQ.add_delay_queue('low_priority_queue', DelayQueue(…, parent='default_queue', priorty=100))

and put your batch notifications through that queue.